As the third generation photovoltaic cell technology, perovskite cells have strong theoretical advantages compared with crystalline silicon and thin film cells due to their material characteristics. The theoretical efficiency is higher, and the theoretical efficiency limit of single-junction perovskite battery can reach 33%, which is higher than the first generation of crystalline silicon battery and the second generation of thin film battery.
Prominent advantages of perovskite battery
As the third generation photovoltaic cell technology, perovskite cells have strong theoretical advantages compared with crystalline silicon and thin film cells due to their material characteristics. The theoretical efficiency is higher, and the theoretical efficiency limit of single-junction perovskite battery can reach 33%, which is higher than that of the first generation crystalline silicon battery and the second generation thin film battery. At the same time, by adjusting the precursor composition, the perovskite band gap is adjustable and the light transmittance is excellent. The perovskite/perovskite stack (45%) and perovskite/crystalline silicon stack (43%) can be prepared, realizing a leap in conversion efficiency; The theoretical cost is lower, the material purity requirement is low, the consumption is small, the theoretical cost of energy consumption is low, and there is still room to reduce the cost of equipment investment after scale; The application scenarios are more diversified, the components can be prepared flexibly, with lightweight advantages, and the terminal application scenarios are diversified; Good response to weak light, high absorption coefficient, and relatively higher conversion efficiency in overcast and indoor weak light conditions; The temperature coefficient is lower, the migration distance of photogenerated carriers is longer, the thickness of perovskite film is smaller, and the effect of temperature on efficiency is low.
Laser equipment is a necessary process in the preparation of perovskite
In order to form a series structure of perovskite battery, different film layers need to be marked at different positions. The scribing of the functional layer can be completed by mask, chemical etching, mechanical or laser scribing. Laser marking can produce a finer marking area. At present, laser marking has gradually replaced other marking methods as the main marking method. At the same time, laser equipment can also be used in the process of perovskite film removal.
P1 process: The TCO substrate at the bottom is divided by laser equipment. After the preparation of the conductive glass electrode TCO layer, before the preparation of the hole transport layer, the perovskite layer and the electron transport layer, the lines are drawn by the laser equipment to form a mutually independent TCO substrate. Laser marking P2 process: cut off the hole transport layer, calcium titanate layer and electron transport layer.
P2 process: Expose the TCO substrate to provide a channel for connecting the positive and negative electrodes of two adjacent sub-cells. After the preparation of the hole transport layer, the calcium titanate layer and the electron transport layer, the hole transport layer, the calcium titanate layer and the electron transport layer are etched by the laser equipment to expose the TCO layer, so that the positive and negative electrodes between the sub-cells can be connected in the next electrode evaporation process.
P3 process: remove part of the functional layer to split the positive pole of the adjacent sub-cell. In order to ensure that the P2 layer is not damaged, this process requires high processing accuracy of the laser equipment.
Laser edge cleaning P4 process: cleaning process before packaging. Laser edge cleaning refers to the use of laser technology to remove the deposited film on the edge of the battery. This technology is relatively mature and can also be applied to thin film batteries. The efficiency of laser edge cleaning is high, but it will cause the mutual melting of the side edges of the film layer, which will lead to short circuit and affect the efficiency and reliability of the battery. Two edge cleaning methods have been developed in the industry to remove the edges of the front electrode and the back electrode respectively to avoid mutual melting.
Problems and solutions of perovskite electrically pumped laser equipment
There are a lot of defects on the surface of perovskite, and the defect assisted single molecule recombination can be effectively weakened by introducing a suitable passivator; The thermal effect in perovskite lasers is serious, which can be alleviated by reducing the device area, using short pulse source excitation, improving the conductivity of each functional layer of the device, and introducing high heat dissipation electrodes; In terms of the structure design of the electrical injection device, the carrier transport materials that are more compatible with the perovskite energy level are selected to improve the charge transport capacity of each function, and optimize the quality of the functional film and interface quality; Optical structure design: reduce scattering loss. On the premise of preparing thin films with low surface roughness, the introduction of recrystallization strategy can effectively reduce surface roughness and reduce pinholes. Reduce the parasitic absorption of metal electrode by enhancing the optical limiting ability of carrier transport layer or nanostructure electrode; The time-accelerating particle number inversion is a useful supplement to the realization of electrically pumped laser.
Source: laserfair
